Efeitos de fontes de carbono e nitrogênio na produção de secretoma de Colletotrichum spp.

Abstract

The present study investigated the effect of carbon and nitrogen limitation on foliar lesions caused by the secretoma of phytopathogenic fungi. Three species of Colletotrichum and their nit mutants were cultured with 10g / L carbon supplementation (dextrose, sucrose, starch and sorbitol) and 1g / L nitrogen (ammonium molybdate, ammonium chloride, potassium nitrate, L-asparagine and extract of yeast). The aim was to identify which sources and combinations cause physiological stress. The diameter of the colonies, spore production, fresh mass, dry matter and its variation, pH variation and leaf protein and lesion production were measured. It was possible to observe that sucrose and inorganic sources of nitrogen caused nutritional stress in fungal isolates, especially the association of sorbitol and potassium nitrate, which best simulates the nutritional stress encountered in the initial stages of infection. The host Sl exhibited a larger and more diverse reaction to the secretoma. In the nit mutants it was observed that sorbitol and yeast extract provided the lowest physiological stresses and the greatest diversity of leaf lesions in Sl. Therefore nutritional stress contributes to the potential harmful and non-specific host, in the Colletotrichum species used in this study, as well as to its nit mutants. However, nutritional stress also evidenced the superior performance of nit mutants in using nitrogen sources that were alternative to nitrate when compared to wild types.